1 Samuel 18:20-21

20Saul had another daughter, Michal, and she loved David. When somebody told Saul about this, he was very happy.

21He thought, ‘I will let David marry her. I will use her as a trap that will catch him. I will give the Philistines a chance to kill him.’ So Saul said to David, ‘Now you have another chance to marry one of my daughters.’